In the week where many celebrated Halloween we are wondering about that tingle down your spine, the dryness in your mouth, the racing pulse - might it actually be good for you? We also look into a special frequency of sound, just below our human hearing range, that might cause rational people to start feeling spooky. And we explore Cryptids and the zoology of creatures that don’t really exist. Plus, if you’re bilingual, do you really have a first and second language? We also explore why driving a taxi is a workout for your brain and look at the benefits and pitfalls of cycling around the world. Presenter: Marnie Chesterton, with Camilla Mota and Godfred Boafo. Producer: Margaret Sessa-Hawkins, with Alex Mansfield, Tom Bonnett and Ben Motley